Performance Evaluation of Ionic Liquids as a Clay Stabilizer and Shale Inhibitor

摘要

Most oil and gas producing formations contain clay minerals that were deposited during the sedimentation process,formed during the interaction of heat,pressure,and time on the naturally present minerals in the formation,or precipitated from fluids flowing from one area of the formation to others.The oil and gas industry has extensively investigated the role of these clay minerals during production and the potential permeability damage that can occur with swelling and migration of these clays.For many years,the effective use of salts such as KCl and NaCl in workover fluids for temporary clay stabilization has been well established.However,due to the potential environmental issues and the logistics of using large quantities of salts for this application,many operators have begun to search for alternative clay stabilizer products.This project details the investigation and evaluation of ionic liquids as a clay stabilizer and shale inhibitor additive to prevent clay swelling and migration in comparison to the industry-standard clay stabilizers.Ionic liquids are compounds that are liquids at ambient temperatures and consist entirely of cations and anions,usually a organic cation and a inorganic anion.Screening studies to determine the state of flocculation of clay-bearing fluids and to screen for shale inhibition were conducted with Capillary Suction Time tests (CST),Clay Pack Flow tests and core flow studies.This paper summarizes the results of the clay stabilizer screening studies conducted with ionic liquids and details the effectiveness of the ionic liquids as KCl substitutes,clay stabilizer additives,and shale inhibitors.